想要下拉列表的javascript验证

Question

I have dropdown which is filled from database

HTML code is :

<asp:DropDownList ID="dd_j_name" CssClass="select2" runat="server" PlaceHolder="Select Journal" AutoPostBack="True" >  </asp:DropDownList>

<asp:ImageButton ID="btn_submit" runat="server" Text="Submit" OnClientClick="return validaterev();" ImageUrl="images/btn-submit1.jpg" />

.cs code is

dd_j_name.DataSource = rr_j_title;
dd_j_name.DataValueField = "EditorId1";
dd_j_name.DataTextField = "Title";
dd_j_name.DataBind();
dd_j_name.Items.Insert(0, "");

My JavaScript code is :

<script language="javascript" type="text/javascript">
 function validaterev() {
     if (document.getElementById("<%=dd_j_name.ClientID%>").value == "Select Journal" || document.getElementById("<%=dd_j_name.ClientID%>").value == "") 
        {
            alert("Required to Select Journal");
            document.getElementById("<%=dd_j_name.ClientID%>").focus();
            return false;
        }

    }
</script>

I am not able to show an alert of JavaScript as even i have not select any other things in dropdown list, what is wrong in my code?

Answer 1

You are getting the value of drop down, hence the value for first element is 0 not "Select Journal", you should try following code

<script language="javascript" type="text/javascript">
 function validaterev() {
     if (document.getElementById("<%=dd_j_name.ClientID%>").value == '0') 
        {
            alert("Required to Select Journal");
            document.getElementById("<%=dd_j_name.ClientID%>").focus();
            return false;
        }

    }
</script>

Hope it helps :)